3MQ0

Crystal Structure of Agobacterium tumefaciens repressor BlcR

Summary for 3MQ0

• Entry DOI: 10.2210/pdb3mq0/pdb
• Descriptor: Transcriptional repressor of the blcABC operon (2 entities in total)
• Functional Keywords: helix-turn-helix, gaf fold, transcription repressor
• Biological source: Agrobacterium tumefaciens
• Total number of polymer chains: 2
• Total formula weight: 59629.77

Authors

Chen, L. (deposition date: 2010-04-27, release date: 2011-03-30, Last modification date: 2024-02-21)

Primary citation

Pan, Y.,Fiscus, V.,Meng, W.,Zheng, Z.,Zhang, L.H.,Fuqua, C.,Chen, L.
The Agrobacterium tumefaciens Transcription Factor BlcR Is Regulated via Oligomerization.
J.Biol.Chem., 286:20431-20440, 2011

PubMed Abstract: The Agrobacterium tumefaciens BlcR is a member of the emerging isocitrate lyase transcription regulators that negatively regulates metabolism of γ-butyrolactone, and its repressing function is relieved by succinate semialdehyde (SSA). Our crystal structure showed that BlcR folded into the DNA- and SSA-binding domains and dimerized via the DNA-binding domains. Mutational analysis identified residues, including Phe(147), that are important for SSA association; BlcR(F147A) existed as tetramer. Two BlcR dimers bound to target DNA and in a cooperative manner, and the distance between the two BlcR-binding sequences in DNA was critical for BlcR-DNA association. Tetrameric BlcR(F147A) retained DNA binding activity, and importantly, this activity was not affected by the distance separating the BlcR-binding sequences in DNA. SSA did not dissociate tetrameric BlcR(F147A) or BlcR(F147A)-DNA. As well as in the SSA-binding site, Phe(147) is located in a structurally flexible loop that may be involved in BlcR oligomerization. We propose that SSA regulates BlcR DNA-binding function via oligomerization.

PubMed: 21467043
DOI: 10.1074/jbc.M110.196154

Experimental method

X-RAY DIFFRACTION (1.793 Å)